Variable camber propeller



Nov. 1, 1932. A. E. MILLER ET AL VARIABLE CAMBER PROPELL ER Filed Feb.l6, 1931 '2 Sheets-Sheet 1 INVENTORS Ar tlzu/r EZMLLl/er and HarveyMSalisbury By E ATTORNEY Nov. 1, ,1932. A. E. MILLER ET AL 1,336,289

vAfiIABLE CAMBER PROPELLER Filed Feb. 16, 1931 2 Sheets-Sheet 2INVENTORS Apzhuk EiMiLler mad Hruey By G g g ATTORNEQY Patented Nov. 1,1932 ARTHUR E. MILLER, OF SACRAMENTO, AND

WALNUT GROVE, CALIFORNCI HERVEY m. SALISBURY, or

VARIABLE CAMBER PROPELLER Application filed February '16, 1931.

This invention relates to airplanes, and particularly to theconstruction of the propellers of the same. In effect a propeller isnothing more than a wing. or in other words the propellers action orlift is caused by driv-- mg an airfoil through the air. Since bychanging the camber of a wing it is possible to change its liftingeffect, the same holds true of a propeller. \Vc make use of this fact inthe present invention, the principal object of which is to construct theblades of a propeller so that they have adjustable trailing edgeportions in order that the camber or transverse form of the blades maybe altered; and'to provide a means whereby these edge portions may beadjusted by the pilot and mechanically held in any position while theairplane is in flight.

The same principle may also be applied to lifting propellers orhelicopters, or to supporting wing units.

A further object of the invention is to produce a simple and inexpensivedevice and yet one which will be exceedingly effective for the purposefor which it is designed.

These objects we accomplish by means of such structure and relativearrangement of parts as will fully appear by a perusal of the followingspecification and claim.

In the drawings similar characters of reference indicate correspondingparts in the several views:

Fig. l is a fragmentary side outline of an airplane, showing ouradjustable camber propeller and the means for adjusting the same.

Fig. 2 is an enlarged fragmentary side view of the propeller and itscontrol means.

ig. 3 is a top plan view of the structure, partly in section, showingthe propeller blade elements in their normal position.

Fig. 4 is a similar view, showing the camber of the blades increased.

Referring now more particularly to the characters of reference on thedrawings, 1 5 denotes the fuselage of an airplane, from the front end ofwhich the drive shaft 2 projects from the motor as usual. This shaftprojects forwardly a slightly greater distance than in ordinarypractice, and on its forward end is fixed a standard hub 3, in theopposed Serial No. 5:5,ai5.

bosses 30: of which are fixed ends of the opposed blades 4. The bladesmay be of conventional form, except that their rearor trailing edgeportions 5 are formed separate from the main blade portions, and arehinged thereto along their adjacent edges by shafts 6, which extendlengthwise of the blades as clearly shown.

These shafts extend beyond the portions-5 inwardly of the outer ends ofthe hub bosses 6o 1n overhanging clearance relation thereto. At theseends the shafts are rigidly connected to the adjacent ends of pylons 7,which extend thence rearwardly in overhanging relation to the hub on theopposite sides of the same. At their rear ends the pylons are pivoted onthe forward ends of the longitudinally adjustable links 8, which attheir rear ends are swivellyconnected to the outer ends of arms 9, whichproject oppositely and radially from a collar 10. This collar isslidably splined on the shaft 2 so as to be I always maintained in thesame relation to the propeller. This collar is engaged by a yoke 11,there being anti-friction bearings 12 of 7 the annular and thrust typebetween the collar and yoke, so that the resistance to relative rotationis reduced to a minimum.

The shift fork 13, which is pivoted intermediate itsends on to thefuselage or motor, is connected to the yoke and has a control rod 14leading thence to the pilots compartment of the airplane. At this endthe rod is connected to a control lever 15, which is provided with apawl and ratchet mechanism indicated at 16 so that it may be heldimmovable in any position.

It will, therefore, be seen that by shifting the lever in one directionor the other, the air entering surfaces of the propeller blades will besimultaneously changed from a normal camber as shown in Fig. 3, to agreater cambe! or one of convex form, as shown in Fig. 4; or the cambermay be made relatively concave as indicated in Fig. 3, thereby tendingto '0 negative the forward propelling action of the propeller and exert.a braking effect.

For taking off or for climbing, where the maximum en inc and propellerspeed is desired, the cam er or section of the airfoil (the 1 isflattened out, while for speed and cruising the camber, is increased andthe engine speed may be lessened. The camber adjusting action we feelwill give better or more practical results than can be obtained byadjusting the pitch of the propeller blades as a whole, since such formof adjustment tends at times to stall the engine, if not handled verycarefully. With the adjustment of the camber on the other hand, thepropeller blades retain their normal, easy lead into the air at alltimes, any difference of the thrust being had only in the trailing edgesof the blades. Also this arrangement enables the blades themselves to berigidly mounted so that there is no tendency for any excessive vibrationor misalignment to be had as is the propeller) case when the propellersare turnable in the hub.

From the foregoing description it will be readily seen-that we haveproduced such a device as substantially fulfills the objects of theinvention as set forth herein.

While the specification sets forth in detail v the present and preferredconstruction of the device, still in practice such deviations from suchdetail may be resorted to as do not form a departure from the spirit ofthe invention, as defined by the appended claim.

Having thus described our invention what we claim as new and useful anddesire to secure by Letters Patent is:

A propeller comprising main blade portions and trailing edge portionsinitially separate therefrom, hinge means between the blade portionsincluding shafts secured to the trailing edge portions and projectingbeyond the inner ends of the same, a hub having laterally extendingportions from which the main blade portions project, the shafts overhanging said rigidly connected to the projecting ends of the shafts andextending rearwardly and laterally of the blades on opposite sides ofthe hub, a shaft projecting rearwardly from the hub, a collar splined onsaid shaft, opposed arms projecting outwardly from the collar, linksparallel to the shaft flexibly connecting said arms and pylons, thelatter being positioned so as to be concealed from in front by thelateral hub portions, and means to slide the collar along the shaft.

In testimony whereof we affix our signatures.

ARTHUR E. MILLER; HERVEY M. SALISBURY.

lateral hub portions, pylons 1

